Preterm birth affects about 10% of pregnant women and accounts for 75% of perinatal mortality and 50% of long-term neurological handicap. Preterm birth disproportionately affects minority women, and mortality rate in black neonates is twice that in white. Use of invasive recording techniques in experimental animals (pregnant monkey and baboons) have enabled us to identify patterns of myometrial activity that are ominous in terms of potential premature birth and patterns that are innocuous. Our hypothesis is that myometrial activity of both the labor and delivery contraction type and the low amplitude contracture type is accompanied by changes in transabdominal electrical impedance (EI). We have been able to obtain data in pregnant women in labor to show good correlation between intrauterine pressure (IUP) changes and El changes. Invasive registration of IUP in pregnant women at risk for preterm birth cannot be performed over several days. Thus long-term studies must be carried out in pregnant nonhuman primates. We propose to use the chronically instrumented pregnant baboon, an animal preparation with which we are experienced, to compare invasive methods of registering myometrial activity and EI. This proposal if funded, would allow us to determine the suitability of EI for registration of the two major types of myometrial activity that we have recorded in pregnant nonhuman primates. The intended outcome of this feasibility study is to design instrumentation that can be used in the home monitoring situation for both diagnosis of premature labor and to monitor therapy. Preterm labor is the major problem of obstetric care. To date there is no universally suitable instrumentation to monitor the patient at risk. Design of effective monitoring equipment would greatly assist the obstetric management of preterm labor.